This invention lies in the field of pool cleaners which are driven by water circulated by a pump. The invention is not necessarily limited to xe2x80x9cautomatic pool cleanersxe2x80x9d, depending on what precisely is understood by this term, but the term xe2x80x9cautomatic pool cleanersxe2x80x9d is often used in the context of pool cleaners with which this invention is primarily concerned. Although the words xe2x80x9cpool cleanersxe2x80x9d will be used for convenience in this specification, they are to be interpreted broadly, as not limited to cleaning of domestic pools, but to include other bodies of water in which a cleaning and/or stirring action is required. The art in this field is divided into two parts, namely suction side cleaners and push side cleaners, referring to the suction and push sides respectively of a pump system which circulates water in the pool. The present invention lies primarily though not exclusively, in the push side part of the art, the term xe2x80x9cpressure side cleanersxe2x80x9d is also used to refer to the same push side cleaners.
Push side pool cleaners are distinguished from suction side cleaners, for various reasons known in the art; an example of a push side cleaner is described in South African patent 85/0648, granted to Alopex Industries, marketed as the xe2x80x9cPOLARISxe2x80x9d (trademark).
Whereas suction side cleaners have an effective wiping or rubbing action on the pool surfaces, this is a shortcoming with push side pool cleaners of the present art which run on wheels with a venturi passage passing over the pool surfaces with a clearance between the mouth of the venturi and the pool surface.
Again, whereas suction side pool cleaners have few moving parts, the cleaner moving over the pool surfaces under impulsion of intermittent water flow caused by an oscillating tongue, or a suction tube whose wall collapses intermittently, for example, certain push side pool cleaners of the art have the disadvantage that they are moved by means of a water turbine driving the wheels through a drive train consisting of many gears and shafts.
Also, whereas suction side cleaners remove very small particles from the pool because the particles picked up are passed through the main pool filter, push side pool cleaners of the art do not pass particles through the main pool filter, but through a bag filter attached to the cleaner; dust size particles pass the apertures of bag type filters to re-enter the pool water, so that these cleaners must rely on stirring up these dust size particles so that they remain sufficiently in suspension to be drawn into the pool weir and thence to the main pool filter.
Whereas suction side cleaners are xe2x80x9cadd onxe2x80x9d products, which the owner of an existing pool and filtering system can add on without technical assistance, most push side cleaners of the present art are initially set up by a technically capable person, where they are connected to a booster pump in the main pool filter circulation system, or into a dedicated water circulation system. Hence push side pool cleaners of the art tend to be sold via contractors who are building a pool and circulation system.
Although push side pool cleaners do have potential for less interference with the desirable randomness of movement over the pool surfaces, due to a smaller diameter hose being acceptable, than suction side cleaners, much of this potential advantage is lost by the wheeled drive of these cleaners of the push side cleaner art which tend to provide straight line travel. The POLARIS cleaner has three wheels asymmetrically arranged to try to reduce this effect, for example. There is a continuing need in the art for better randomness of movement of the cleaner over the pool surfaces, leading to better cleaning.
The push side water flow is given a bypass valve at the pool side allowing water flow to the cleaner to be adjusted by increasing or decreasing the bypass, so as to get an acceptable speed of movement of the cleaner over the pool surfaces. A disadvantage of this arrangement of the art is that the energy of the bypassed flow is discarded.
Finally, all present pool cleaners have limitations as to the shallowness at which they will operate and as to their ability to negotiate formations like stairs in pools without becoming stuck in one position. It is desirable that pool cleaners work in shallower regions and thus negotiate formations like stairs better.
Thus there exists a need to address these limitations and problems in push side cleaners of the art at least to some extent.
The present invention provides a push side cleaner which is generally spherical or prolate or otherwise spheroidal in the shape of its outer surfaces (or otherwise expressed, the cleaner outer surfaces conform with a conceptual outer envelope of spherical or prolate spheroidal shape). The invention can also be implemented in an outer shape which conforms to two truncated cones both tapering outwardly from a central region of the cleaner, for convenience the term xe2x80x9cbi-conicalxe2x80x9d will be used in the description and claims to briefly refer to this shape. The invention can also be implemented in a cylindrical shape.
These shapes can comprehensively be described as a family of solids of revolution and other similar shapes, lying between the spherical/spheroidal, conical and cylindrical are also accommodated within the scope of the invention. In this description the term spheroidal only will henceforward be used for convenience, comprehending within its scope also the meaning indicated in the preceding sentence.
A central zone of the spheroidal shape bounded by two segments of the spheroid on each side will form the total outer shape. The central zone will have a push side hose connected to it and the two segments will be rotatively driven on either side to provide impulsion to the cleaner for moving it over the pool surfaces to be cleaned. The central zone will have a clearance from the pool surfaces and will accommodate a venturi or other suction passage for drawing in debris from the pool surfaces.
The two segments may be independently driven, or there may be advantage in linking them by a shaft so that they rotate being fixed relative to each other.
Thus a feature of the cleaner of this invention is that the spheroidal surfaces of the two segments will provide impulsion to move the cleaner over the pool surface, wherever these surfaces engage the pool surfaces and in whatever orientation the cleaner happens to be. In this sense, then, the cleaner of this invention is capable of providing impulsion to the cleaner in three dimensions; by contrast, the pool cleaners of art, both of the push side and of the suction side types, are confined to impulsion only in two dimensions. The cleaners of art must remain oriented with their wheels or foot against the pool surfaces, if they capsize, they are, like a conventional vehicle, unable to move, until righted. By contrast the cleaner of this invention can turn any way round relative to the pool surfaces, be they horizontal or vertical, and still provide impulsion. Furthermore, this three dimensional character of the motivation capability of the cleaner of this invention provides a dramatic enhancement of the ability to achieve more random movement over pool surfaces. The spheroidal surface interacts with the pool surfaces with an additional dimension of randomness i.e. the third dimension in addition to the two dimensions of the pool surface. The cleaner is in fact more unstable than one on wheels or a foot (a foot is used in suction side cleaners) and gives better randomness. For example, when the cleaner engages a wall of the pool surfaces, it has the capacity for the axis on which the two segments were rotating over the pool floor, to swing with three dimensions of freedom to a new orientation, giving enhanced randomness of movement. In a practical embodiment which has been subjected to extensive testing, the three dimensional movement can be described to occur with respect to an axis of the push side hose connection : these are, firstly around the axis, secondly swinging the axis to left and right and thirdly swinging the axis up and down. The randomness of movement is known in the art to be important, in order to result in cleaning of all of the surface to be cleaned, over a period of time, non-random movements leave xe2x80x9cdeadxe2x80x9d spots which remain uncleaned.
Portions of the spheroidal surfaces of the segments may have brush like formations, e.g. bristles, on them, to give a brushing effect.
Preferably the pool cleaner having the features of this invention is made with a specific gravity closer to 1 than is appropriate in cleaners of the art. This is made possible by the three dimensional character of the movement of the cleaner of this invention.
The effective or net force acting on the cleaner, when the cleaner is under water, may be made to pass through a point located on the opposite side of the axis of rotation of the cleaner as a mouth of the suction passage. This may be done with floats, e.g. sealed volumes containing air) located on the same side of the axis of rotation of the cleaner as the mouth. The cleaner may still have a centre of gravity when outside water which centre is on the same side of the axis as the mouth. However, when submerged, the buoyancy of the floats reverses the position of the net force acting on the cleaner to the opposite side of the axis as the mouth. The effective or net force acting on the cleaner when submerged can be assessed by constructing the vector sum of the gravitational forces and the buoyancy forces.
This counter intuitive approach results in a less stable device under water, which is tolerable by virtue of the spheroidal shape of the cleaner of this invention. The lower stability results in more random movement over the pool surface which in turn gives the advantage, as mentioned, of less tendency for the cleaner to repeatedly miss some areas, leaving them uncleaned.
A feature of this invention, whether the floats are used, or not, is that the centre of gravity is made closer to the axis of rotation of the cleaner than is appropriate in cleaners of conventional design. This feature again reduces stability and as a result brings the beneficial advantage of greater randomness than is achieved in conventional cleaners. This is possible simply for the reason already stated, that spheroidal shape gives the advantage that the cleaner can not xe2x80x9ccapsizexe2x80x9d into a position in which it can no longer move, like a conventional vehicle.
The degree of buoyancy of the hose may be selected, for example, to achieve a desirable balance between a tendency to work well on the bottom surfaces of the pool, on the one hand, and also on the wall surfaces, on the other.
The cleaner of this invention may be given a jet which impels the cleaner against the pool surfaces with a mouth of the suction passage in proximity to the pool surfaces, achievable both on upright as well as horizontal parts of the pool surfaces.
Preferably the passage is given a direction, at least near the mouth of the passage, which has a tangential component as well as a radial component. In other words, the venturi passage, at least near its mouth, is preferably not normal (at right angles) to the spheroidal outer surfaces of the cleaner. The passage is oriented so that the mouth is directed in the direction in which the cleaner moves. This gives a degree of scooping action, helpful to lifting debris from the pool surfaces. Jets which provide the suction action in the suction passage, given this tangential component of direction, also assists in the forward impulsion of the cleaner, by jet reaction forces.
This invention further provides a pool cleaner which is driven by direct impulsion of water jets from the push side supply onto vanes on wheels of the cleaner. No drive train is provided or required, there are no gears or drive shafts transmitting a drive to wheels. The spheroidal shaped cleaner, as described above, provides the wheels in the form of the outer segments of the spheroidal shape.
Preferably, this drive feature is provided in the cleaner having a spheroidal outer shape, as described above. The vanes are provided at an inner edge of each segment, with the water jets issuing from nozzle formations provided on the central zone. Low energy losses giving more efficient use of the water energy can be achieved by the judicious application of this aspect of the invention. An advantage that is achievable as a result is that more of the total water energy available from the push side supply can be devoted to the suction function while still leaving sufficient for impulsion of the cleaner. Wearing parts in a drive train are eliminated.
A further feature of the invention, which is preferably implemented with the features described above, is the location of a debris collector inside the spheroidal shape of the cleaner. Conveniently, the debris collector is confined to within the central zone, because this makes it simple to lift the debris collector out of the cleaner to empty it, from time to time. Thus the suction passage leads to the debris collector which is located in the central zone. The debris collector can includes a sump region and must include sieve or screen surfaces to allow the water to exit the collector and retain the debris. The suction passage is therefore preferably curved, leading from the mouth which is oriented with a tangential component of direction, to the collector.
A still further feature of the invention relates to the splitting or division of the water which is supplied to the cleaner via the push side hose between the jets which provide the suction action within the suction passage and the jets which provide the direct impulsion onto the vanes on the wheels. In accordance with the invention, a water flow splitter is provided which comprises two passages which have adjacent entrance mouths, a movable occluding element which is movable to selectable position settings in which one entrance mouth is occluded more or less than the other entrance mouth. The preferred structure for the adjacent entrance mouths is a circular tube with a diametral dividing wall and for the occluding element a cylindrical cup shaped element rotatable in the tube with a bottom of the cup located against the diametral dividing wall and the bottom having a semicircular opening and movable by rotation of the cup shaped element. The occluding element can have markings on it to indicate various optional settings which provide different splits between the driving jets and suction generating jets. There may be grooves and ridges on the occluding element and the adjacent mouths to retain selected settings and the manufacturer or supplier may provide a selected setting to the user.
These splitting arrangements still allow for the water supplied by the push side hose to the cleaner to be provided to a third use, namely the jet which issues external to the cleaner to provide an impulsive force assisting the forward motivation of the cleaner and/or the attachment to a surface to be cleaned.
A beneficial effect of a pool cleaner designed according to this invention, is that a positive pressure is created inside the spheroidal cleaner other than in the suction passage, so that debris which might otherwise accumulate in unwanted spaces does not do so.